At the chemical level, diamonds are no more than carbon atoms aligned in a three-dimensional (3-D) crystal lattice. However, even a seemingly flawless diamond contains defects: spots in that lattice where a carbon atom is missing or has been replaced by something else. Some of these defects are highly desirable; They create a platform for various quantum technologies for advanced computing, secure communication and precision sensing.
Quantum technologies are based on units of quantum information known as "qubits." The spin of electrons are prime candidates to serve as qubits; unlike binary computing systems where data takes the form of only 0s or 1s, electron spin can represent 0, 1, or both simultaneously in a quantum superposition. Qubits from diamonds are quantum-mechanical properties, including superposition, existing at room temperature, unlike many other potential quantum resources.
The practical challenge of collecting information from a single atom deep inside a crystal is a daunting one, however. Penn Engineers expects this problem in a recent study in which they devised a way to pattern the surface of a diamond that makes it easier to collect light from the defects inside.
The research was led by Lee Bassett, Assistant Professor in the Department of Electrical Engineering and Systems, graduate student Tzu-Yung Huang, and postdoctoral researcher Richard Grote from Bassett's lab.
Additional Bassett Lab members David Hopper, Annemarie Exarhos, and Garrett Kaighn contributed to the work, as did Gerald Lopez, Director of Business Development at the Singh Center for Nanotechnology, and two members of Amsterdam's Center for Nanophotonics, Sander Mann and Erik Garnett.
The study published in Nature Communications .
The key to harnessing the potential power of quantum systems is to be able to create the quantum state of the matter is considered to be "electronically suspended".
Bassett's lab approaches this challenge from a number of directions. Recently, the lab developed a quantum platform based on a two-dimensional (2-D) material called hexagonal boron nitride which, due to its extremely thin dimensions, allows for easier access to electron spins. Electron spins: diamonds.
Small defects in diamonds, called nitrogen-vacancy (NV) centers, are known to harbor electron spins that can be manipulated at room temperature. Each NV center gives that information about the spin's quantum state.
Bassett explains why it is important to consider both 2-D and 3-D avenues in quantum technology:
"The different material platforms are at different levels." Defects in 2-D materials are ideally suited for proximity sensing on surfaces, and they may eventually be used for other applications, such as integrated quantum photonic devices, "Bassett says. "Right now, however, the diamond NV center is simply the best platform for room-temperature quantum information processing."
So far, it has only been  Unfortunately, those deeply embedded NV centers are not very easy to access on the surface of the diamond. Collecting light from those hard-to-reach defects usually requires a bulky optical microscope in a highly controlled laboratory environment. Bassett's team wanted to find a better way to collect light from NV centers.
"We use the concept of a metasurface to design and fabricate a structure on the surface of a diamond and direct it into an optical fiber, previously required in a large scale, free-space optical microscope, "Bassett says. A complete set of electronics and free-space optical components. "
Metasurfaces consist of intricate, nanoscale patterns that can achieve physical phenomena otherwise impossible at the macroscale. The researchers' metalsens of a field of pillars, each 1 micrometer tall and 100-250 nanometers in diameter, are arranged in such a way that they are light-like like a traditional curved lens.
"The actual metalens is about 30." The actual metalens is about 30 At most, you could see a dark speckle, "says Huang. "We typically think of lenses as focusing or collimating, but, with a metastructure, we have the freedom to design any kind of profile that we want at NV center, which is not possible, or is very difficult, with free-space optics. "
To design their metalens, Bassett, Huang and Grote had to assemble a team with a diverse array of knowledge, from quantum mechanics to electrical engineering to nanotechnology. Bassett credits the Singh Center for Nanotechnology as a critical role in their ability to physically construct.
"Nanofabrication is a key component of this project," says Bassett. Diamond is a challenging material to process, and it is Richard's dedicated work in the Singh Center that enabled this Metzler, the Thin Film Area Manager at the Singh Center, in developing the diamond etch. "
Although nanofabrication comes with its challenges, the flexibility afforded by metasurface engineering provides important advantages for real-world applications of quantum technology:
"We decided to collate the light from NV centers to go to an optical fiber, as it "interfaces with other techniques have been developed for compact fiber-optic technologies over the past decade," Huang says. Those who opt for the other optical enhancements. "
This study is just one of many steps toward the goal of compacting quantum technology into more efficient systems. Bassett's lab plans to continue exploring how to harness the quantum potential of 2-D and 3-D materials.
"The field of quantum engineering is advancing rapidly now in large part due to the convergence of ideas and expertise from many disciplines including physics, materials science, photonics and electronics, "Bassett says. "Penn Engineering excels in all these areas." Ultimately, we want to transition this technology out of the lab and into the real world where it can have an impact on our everyday lives. "
Engineers develop room temperature, two-dimensional platform for quantum technology
Tzu-Yung Huang et al., A monolithic immersion metal ion for imaging solid-state quantum emitters, Nature Communications (2019). DOI: 10.1038 / s41467-019-10238-5
Engineers design nanostructured diamond metal for compact quantum technologies (2019, June 11)
retrieved 12 June 2019
This document is copyrighted. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is for information purposes only.